1. Field of the Invention
The present invention relates to a control process suitable for a motor driving control unit for a motor having a relatively small power source capacity and a relatively low normal load, and exhibiting a relatively high required maximum output.
2. Description of the Related Art
There is a known control process in the motor driving control unit, which is generally called a map control process. In this map control process, control values based on characteristic data for the motor are previously stored on a map, and a control value is read from the map in accordance with an operational state and interpolated to give a motor driving signal. The map control processes include one example disclosed, for example, in Japanese Patent Application Laid-open No. 5-153705.
In an electric vehicle, a solar car or the like, the power source capacity of a motor driving power source is relatively small and for this reason, the power source voltage of the motor driving power source is largely varied due to a variation in load, a load driving time, a charging by receiving of a regenerative operation and the like. In the map control process described in Japanese Patent Application Laid-open No. 5-153705, to deal with such variation in power source voltage, a plurality of power source voltages of the motor driving power source are previously set and a plurality of control command value maps corresponding to the power source voltages are previously made, so that an output command value is provided in accordance with the variation in power source voltage from a corresponding control command value map, or if the corresponding control command value map does not exist, then an interpolating calculation is carried out to provide an output command value. Therefore, to perform a motor driving control with a high accuracy and a high efficiency, not only an increased memory capacity, but also a high calculation speed is required, bringing about increases in size and cost of the control unit, and resulting in an increased number of steps of sampling characteristic data. In the existing circumstances, therefore, reductions in control accuracy and efficiency are permitted to reduce the number of control command value maps established to a relatively small number, and it is obliged to use a control unit having a relatively low calculation speed.